The present invention relates to a semiconductor module and producing method therefor.
In a prior art semiconductor module, an electrically conductive layer, an electrically insulating layer and an electric element connected electrically to the electrically insulating layer are mounted on a rigid (great thickness) substrate.
An object of the present invention is to provide a semiconductor module whose thickness is minimized while effectively shielding the semiconductor module from a magnetic and/or electric noise, and a producing method therefor.
According to the present invention, a semiconductor module comprises, at least one electric element including a semiconductor chip, an electrically conductive layer connected electrically to the electric element, an electrically conductive joint arranged between the electric element and the electrically conductive layer to connect electrically the electric element and the electrically conductive layer to each other, a molding resin covering at least partially the electric element and the electrically conductive joint, and an electrically insulating layer contacting at least partially the electrically conductive layer.
Since the electric element is supported on the electrically conductive layer and electrically insulating layer without a great thickness substrate, a thickness of the semiconductor module can be minimized.
If the electrically conductive layer includes a front surface and a reverse surface opposite to each other in a thickness direction of the electrically conductive layer, the front surface faces to the electric element (any intermediate member, for example, another electrically conductive layer, the electrically insulating layer, the molding resin, the electrically conductive joint or the like may be arranged between the front surface and the electric element so that the front surface faces to the electric element therethrough), the reverse surface is prevented from facing to the electric element, and a Nickel concentration at the reverse surface is higher than a Nickel concentration at the front surface, the electric element can be effectively shielded from a magnetic noise by the reverse surface of high Nickel concentration while a diffusion of Nickel from the electrically conductive layer to the electrically conductive joint is restrained.
If the electrically conductive layer includes a first layer of Nickel-base metal, and a second layer of Copper-base metal extends at least partially between the first layer and the electric element while being joined with the first layer, the electric element can be effectively shielded from a magnetic noise by the first layer while a diffusion of Nickel from the electrically conductive layer to the electrically conductive joint is restrained. When the electrically insulating layer is juxtaposed with a part of the second layer in a direction perpendicular to a thickness direction of the electrically conductive layer so that surfaces of the electrically insulating layer and the part of the second layer both prevented from facing to the electric element extend along a common flat face, the first layer can extend on the common flat face. When the first layer extends on the surface of the electrically insulating layer along the common flat face, the first layer for effectively shielding the electric element can extend over both the second layer and the electrically insulating layer. When a surface of the first layer prevented from facing to the electric element extends between the electric element and a surface of the electrically insulating layer prevented from facing to the electric element in a thickness direction of the electrically conductive layer, the surface of the first layer is securely protected by the surface of the electrically insulating layer. It is preferable for the semiconductor module to have a solder contacting a surface of the first layer prevented from facing to the electric element so that the surface of the first layer is protected by the solder.
If a film of Nickel-base metal extending on a surface of the electrically insulating layer prevented from facing to the electric element, the electric element can be effectively shielded from the magnetic noise by the film of Nickel-base metal while a diffusion of Nickel to the electrically conductive joint is restrained.
A metallic film electrically connected to the electrically conductive layer and/or magnetically permeable may extend on a surface of the electrically insulating layer prevented from facing to the electric element. The semiconductor module may comprises a plurality of the electric elements including the semiconductor chip and at least one of transistor, diode, electric resistance, inductor, capacitor, crystal-oscillator, filter, balun, antenna, a circuit module and an interface connector.
According to the present invention, a method for producing a semiconductor module, comprising the steps of: preparing a substrate including a metallic surface plated with Nickel-base metal to form a Nickel-base metal film on the metallic surface, forming an electrically insulating layer and an electrically conductive layer on the Nickel-base metal film, connecting electrically the electrically conductive layer to an electric element through an electrically conductive joint arranged between the electric element and the electrically conductive layer, covering at least a part of the electric element and at least a part of the electrically conductive joint with a molding resin, and subsequently, removing the Nickel-base metal film from the metallic surface so that a combination of the Nickel-base metal film, the electrically insulating layer, the electrically conductive layer, the electrically conductive joint and the molding resin is separated from the metallic surface.
Since the metallic surface is plated with Nickel-base (Nickel or Nickel base alloy) metal, the combination of the Nickel-base metal film, the electrically insulating layer, the electrically conductive layer, the electrically conductive joint and the molding resin can be easily and securely separated from the metallic surface at a boundary between the Nickel-base metal and the metallic surface.
In the step of forming the electrically insulating layer and the electrically conductive layer, it is preferable for easily forming a desired pattern of the electrically conductive layer that the electrically insulating layer is formed on a part of the Nickel-base metal film before the electrically conductive layer is formed on the Nickel-base metal film, and subsequently, another part of the Nickel-base metal film on which another part the electrically insulating layer is prevented from being arranged is plated with an electrically conductive material to form the electrically conductive layer on the Nickel-base metal film while the Nickel-base metal film is electrically energized to plate the Nickel-base metal film with the electrically conductive material.
In the step of forming the electrically insulating layer and the electrically conductive layer, it is preferable for easily forming a desired pattern of the electrically conductive layer extending on the electrically insulating layer that the electrically insulating layer is formed on a part of the Nickel-base metal film before the electrically conductive layer is formed on the Nickel-base metal film, a metallic film (of, for example, Copper-Chrome-base-alloy, Copper, Copper-base-alloy or the like) is formed by sputtering on the electrically insulating layer and another part of the Nickel-base metal film on which another part the electrically insulating layer is prevented from being arranged, and the metallic film is plated with an electrically conductive material to form the electrically conductive layer on the metallic film while the metallic film is electrically energized to plate the metallic film with the electrically conductive material.
It is preferable for easy and secure removal of the Nickel-base metal from the metallic surface that a thickness of the Nickel-base metal film is 5-20 xcexcm.
It is preferable for protecting the Nickel-base metal film that another electrically insulating layer is formed on at least a part of a surface of the Nickel-base metal film after the surface of the Nickel-base metal film is exposed by removing the metallic surface from the surface of the Nickel-base metal film.
It is preferable for forming a desired pattern of the Nickel-base metal film that at least a part of the Nickel-base metal film is removed from the combination after the surface of the Nickel-base metal film is exposed by removing the metallic surface from the surface of the Nickel-base metal film. If another part of the Nickel-base metal film remains on a part of the electrically conductive layer and is electrically connected to the part of the electrically conductive layer while the another part of the Nickel-base metal film extends onto a part of the electrically insulating layer, after removing the part of the Nickel-base metal film from the combination, the Nickel-base metal film protects a boundary between the electrically conductive layer and the electrically insulating layer.
It is preferable for securely protecting the surface of the Nickel-base metal film that a solder is heated to be melt and subsequently cooled to be cured on at least a part of the Nickel-base metal film to fix the solder to the at least a part of the Nickel-base metal film after the surface of the Nickel-base metal film is exposed by removing the metallic from the surface of the Nickel-base metal film.
It is preferable for easily and securely separating the Nickel-base metal film from the metallic surface while easily forming the Nickel-base metal film of sufficient thickness that the metallic surface is a stainless steel surface.
It is preferable for preventing powder of the Nickel-base metal film from being scattered that a part of at least one of the electrically insulating layer and the electrically conductive layer is removed along a line on which the Nickel-base metal film is prevented from being arranged, after the Nickel-base metal film is removed from the metallic surface.